This invention relates to devices to discourage the theft of electrical appliances, such as television receivers or stereo components.
More particularly, this invention relates devices to discourage the theft of electrical appliances by reason of having a notice thereon that once the appliance is disconnected from its source of power it will be inoperative until special, undisclosed adjustments are made to the device.
Still more particularly, this invention relates to devices connected in circuit arrangement with the electrical circuit of an electrical appliance to permit the appliance to be operated after the appliance circuit is connected to a source of power and the device is activated, and to prevent the appliance from being operated after the appliance is disconnected from its source of power unless the device is activated.
Numerous anti-theft devices have been developed in the past. A few of the patents which describe such devices are as follows: King, U.S. Pat. No. 3,289,194; Tellerman, U.S. Pat. No. 3,425,050; Cones, U.S. Pat. No. 3,537,095; Fistell, U.S. Pat. No. 3,553,673; Whalen et al, U.S. Pat. No. 3,710,371; and Lowry, U.S. Pat. No. 3,765,008.
The theft of television sets, stereo components, and other major electrical appliances from motels, hotels, and homes has been increasing greatly. The recognition by the public of this increase in crime has brought about the development of many types of anti-theft devices. The theft of electrical appliances from motels and hotels is particularly serious, and most of the anti-theft devices either incorporate alarm means within the appliance itself, or alarm means at a central location. The previous anti-theft alarm devices have been usually quite complex and, because of this complexity, were easily detected and made inoperative by the intended thief. Also, those devices which did include some type of alarm means, as in all the patent references cited above, usually included a battery in addition to the alarm means. And, they usually included some type of switching means, such as a relay, which activated the secondary circuit as soon as the condition of the appliance was changed, as by being disconnected from its primary source of electrical power or by being moved.
An alarm system, either one incorporated within the appliance or one situated at a central location, has the distinct disadvantage of disturbing other guests of the motel or hotel when the appliance is moved, even if the burglary is unsuccessful.
Most of these prior art devices are unsatisfactory and impractical because they are either too complicated to manufacture at a resonable price or are too difficult to maintain. Those systems which include a battery to operate the secondary circuit require constant surveillance by maintenance personnel in order to replace the batteries before they deteriorate with age. Obviously, if the battery has already deteriorated, the alarm device itself will not operate and the burglary is a simple matter.